CN111032623B - Process for purifying long-chain amino acid - Google Patents
Process for purifying long-chain amino acid Download PDFInfo
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- CN111032623B CN111032623B CN201880054827.7A CN201880054827A CN111032623B CN 111032623 B CN111032623 B CN 111032623B CN 201880054827 A CN201880054827 A CN 201880054827A CN 111032623 B CN111032623 B CN 111032623B
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- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
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- C07C227/38—Separation; Purification; Stabilisation; Use of additives
- C07C227/40—Separation; Purification
- C07C227/42—Crystallisation
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C227/00—Preparation of compounds containing amino and carboxyl groups bound to the same carbon skeleton
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- C07C227/40—Separation; Purification
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Abstract
The invention discloses a process for recrystallizing and purifying long-chain amino acid in an organic carboxylic acid aqueous solution with or without a solvent, which comprises the following steps: (1) Dissolving a long-chain amino acid in an aqueous solution of an organic carboxylic acid by heating; (2) Cooling the solution in step (1) to crystallize to obtain long-chain amino acid; (3) And (3) carrying out solid-liquid separation to obtain the long-chain amino acid in the step (2).
Description
Cross-referencing
This application is a continuation of U.S.15/686,500, 8/25, 2017, the contents of which are incorporated by reference.
Technical Field
The invention relates to a process for purifying long-chain amino acid, in particular to a process for purifying long-chain amino acid by recrystallization in an acid aqueous solution.
Background
The long-chain saturated aliphatic amino acid is an important intermediate for producing long-chain nylon. Because of their unique molecular structures, long chain nylons have excellent physical properties, such as: higher mechanical strength, low moisture absorption, excellent oil, low temperature, abrasion and chemical resistance than metals, and very important is easy workability. The long-chain nylon can be processed into various plastic products, and can also be spun into fibers or stretched into films. Long chain nylons are also used in the coating and hot melt adhesive applications. Therefore, the long-chain nylon has wide application in the fields of automobiles, electric power, electronics, communication, petrochemical industry and aviation.
Among the long-chain amino acids, especially 9-aminononanoic acid and 11-aminoundecanoic acid, are used as corresponding monomers for the production of nylon 9 and nylon 11. In addition, the 12-aminododecanoic acid, which has only recently been prepared from laurolactam, may also be used to produce another important engineering plastic, nylon 12.
In order to use these long chain amino acids in the production of polyamide or nylon materials, they need to be purified to a purity level that can be used for polymerization. Some purification methods have been reported.
The first process is crystallization purification of long chain amino acids in water. US2462855 provides a method for purifying 11-aminoundecanoic acid, yielding 53 parts of a long chain amino acid from 1500 parts water. By concentrating the mother liquor, 4 parts of long-chain amino acid can be recovered. However, the process of purification by crystallization in such a dilute solution is relatively low in economical efficiency, and the energy consumption during the concentration is also high.
CN103804209A discloses a recrystallization method for dissolving 11-aminoundecanoic acid in 10 times boiling water. From the solubility of 11-aminoundecanoic acid reported in US2462855, it is difficult to completely dissolve the solution of 11-aminoundecanoic acid during the process of purification with water, and therefore it is difficult to completely separate the impurities by filtration during recrystallization.
US2674607 provides a method for purification of 9-aminononanoic acid by recrystallization in boiling water.
The second process is to recrystallize and purify the long-chain amino acid in an aqueous ethanol solution. GB953621 provides a process for purifying 10-aminodecanoic acid by recrystallization from 80% aqueous ethanol.
US5498733 provides a method for purifying 11-aminoundecanoic acid by first recrystallizing the crude product in water and then in aqueous ethanol (ethanol: water = 3:1). The weight of water and ethanol aqueous solution used for recrystallization was 122 times and 62 times the weight of amino acid, respectively.
US5434307 and US5530148 provide a recrystallization process of 12-aminododecanoic acid in aqueous ethanol (ethanol: water = 1:1) with 87% recovery.
In a third process, 9-aminononanoic acid is purified by crystallization from aqueous acetone. Kohlhase et al (J.Am.oil Chemist's Soc.,1970, vol.47, pp183-188) provide a recrystallization process for crude 9-aminononanoic acid, which is crystallized from 50% aqueous acetone with a 74% recovery. The total amount of solvent used is 130 times the weight of 9-aminononanoic acid.
Perkins et al (J.Am. Oil Chemist's Soc.,1975, vol.52, pp 473-477) reported an improvement to Kohlhase et al purification by dissolving 9-aminononanoic acid in hot water to form a 10% solution of 9-aminononanoic acid, treating with activated carbon and celite, filtering, and cooling the resulting solution and mixing with an equal volume of acetone to precipitate the amino acid. The patent also teaches that the product obtained from water or aqueous acetone is fine hydrophilic amino acid crystals, which are coated with a mother liquor. Crude amino acids usually need to be recrystallized twice and the resulting product is suitable for polymerization.
Finally, miller et al (Ind. Eng. Chem. Prod. Res. Develop. 1971, vol.10, pp442-447) studied the purification of 9-aminononanoic acid in detail, comparing the crystallization of the amino acids in aqueous solutions of acetone, tetrahydrofuran, N-dimethylformamide, respectively. The crystallization of 9-aminononanoic acid requires large amounts of organic solvents.
In view of the foregoing, there is still a need to find a suitable recrystallization solvent for purifying long-chain amino acids and making the purified amino acids suitable for polymerization to produce polyamides or nylons. Since the solubility of long-chain amino acids in water and organic solvents is relatively low, a large amount of water or an aqueous organic solvent solution must be consumed to dissolve the amino acids. Therefore, purification of amino acids according to the prior purification techniques requires a large amount of energy for concentration of mother liquor and recovery of solvent, and is economically disadvantageous.
The object of the present invention is to overcome the drawbacks of the existing long chain amino acid purification techniques and to have further advantages, which will be apparent from the following description.
In the process of the invention, the recrystallization purification of the long-chain amino acid can be carried out at high concentration, and the obtained product has high purity, simple crystallization process and good industrial economy.
Disclosure of Invention
The invention relates to a process for purifying long-chain amino acid, which is used for purifying the long-chain amino acid by recrystallization in an acid aqueous solution. The long chain amino acids have the following structure:
wherein: m is an integer of 6 to 20; r 1 And R 2 Are respectively H or C 1 -C 12 Alkyl group of (1). The long-chain amino acid can be a single compound or a mixture of two or more isomers.
In one embodiment of the present invention, the long-chain amino acid is purified by recrystallization from an aqueous organic carboxylic acid solution. Suitable organic carboxylic acids include: formic acid, acetic acid, propionic acid, butyric acid, glycolic acid, lactic acid, malic acid, tartaric acid, citric acid, and mixed acids of two or more of the above acids. Preferably acetic acid or propionic acid. Most preferred is acetic acid.
It has surprisingly been found that long chain amino acids have a very large solubility in dilute aqueous acetic acid and therefore recrystallization can be carried out at high concentrations. FIGS. 1 and 2 are the solubility curves of 11-aminoundecanoic acid and 12-aminododecanoic acid in water and two different concentrations of aqueous acetic acid (5% wt/wt and 10% wt/wt), respectively. Obviously, a long-chain amino acid which is hardly soluble in water can be dissolved in a dilute acetic acid solution, and for example, the concentration of 11-aminoundecanoic acid in a 10% aqueous acetic acid solution can be 45% at 80 ℃. According to the process of the present invention, such recrystallization at high concentration enables the purification process to be operated simply and industrially economically well.
Although acetic acid can significantly improve the solubility of long chain amino acids in water, it does not form acetate salts with long chain amino acids. When 11-aminoundecanoic acid and 12-aminododecanoic acid were crystallized from deionized water and 10% acetic acid in water, respectively, the resulting products had the same melting points, and the melting point data are shown in table 1. After sufficient drying, the product had virtually no acetic acid residue by gas phase analysis. The product obtained by crystallization from an aqueous acetic acid solution is dissolved in water, and the solution is neutral without adjusting the pH of the solution with an alkaline reagent such as an alkaline hydroxide or aqueous ammonia.
TABLE 1 melting points of 11-aminoundecanoic acid and 12-aminododecanoic acid acetates
In the invention, the crude long-chain amino acid is purified by crystallization in an aqueous acetic acid solution. The concentration of the aqueous acetic acid solution may be 1-95% (wt/wt), preferably 2-80% (wt/wt), more preferably 2-50% (wt/wt), most preferably 5-15% (wt/wt). When the concentration of acetic acid is too high, the recovery of the product may be reduced.
The amount of aqueous acetic acid is sufficient to solubilize the crude long chain amino acid, and the skilled artisan can select an appropriate amount by means of a solubility curve. The amount of aqueous acetic acid solution may thus be 1 to 10 times, preferably 2 to 8 times, more preferably 3 to 5 times the weight of the crude long chain amino acid. When the amount of the aqueous acetic acid solution is excessively large, the recovery rate of the product may be reduced.
The temperature at which the crude long chain amino acid is dissolved in the aqueous acetic acid solution may be from room temperature to the boiling temperature of the solution, preferably from 50 to 100 deg.C, more preferably from 60 to 95 deg.C, and most preferably from 80 to 90 deg.C.
After the crude long-chain amino acid is dissolved, activated carbon or a filter aid can be added to remove pigments and adsorb impurities. After filtration at the preferred temperature, a clear solution can be obtained.
The method of cooling crystallization is well known, and the acetic acid aqueous solution containing long chain amino acid is cooled, crystals begin to precipitate, and then the suspension solution is further cooled to room temperature or lower to complete the crystallization process.
The precipitated long-chain amino acid crystals are subjected to solid-liquid separation (such as filtration or centrifugation) to obtain a product. Washing the obtained solid with acetic acid water solution or deionized water to obtain the high-purity long-chain amino acid product.
In the present invention, the acetic acid solution used for recrystallization may also contain other solvents. Solvents which may be present include methanol, ethanol, propanol, isopropanol, tert-butanol, acetone, butanone, tetrahydrofuran, dioxane, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, or mixtures of two or more of the foregoing solvents. The addition of these solvents to the aqueous acetic acid solution may help to remove impurities and improve product quality.
In another embodiment of the invention, the long chain amino acid is purified by an intermediate by forming the corresponding inorganic acid salt intermediate in an aqueous solution of an inorganic acid. Suitable acids may be sulfuric acid, hydrochloric acid, hydrobromic acid, nitric acid, phosphoric acid, and mixtures of two or more of the foregoing. Preferably the mineral acid is sulfuric acid.
When 11-aminoundecanoic acid and 12-aminododecanoic acid are crystallized from a solution of sulfuric acid, hydrochloric acid and nitric acid, the salts formed are separated off separately. These salts have their characteristic melting points, see table 1. These salts have strong acidity when dissolved in water, and neutral amino acids can be obtained by neutralization with an alkaline agent.
FIG. 3 is a graph of the solubility of 11-aminoundecanoic acid and 12-aminododecanoic acid in 1M sulfuric acid as bisulfate salts. At temperatures below 40 ℃, the bisulfate salts of these two long chain amino acids are almost insoluble, but their solubility rapidly increases as the temperature rises from 60 ℃ to 80 ℃ or higher. This solubility property of bisulfate provides a simple and economical method for purifying crude long chain amino acids via bisulfate intermediates with high product recovery.
In the process of the present invention, the crude long chain amino acid is purified by recrystallization in aqueous mineral acid by forming a mineral acid salt intermediate with the mineral acid, preferably sulfuric acid. The molar ratio of sulfuric acid to long chain amino acids may be 0.1 to 10, preferably 0.5 to 5, more preferably 0.5 to 2, most preferably 0.9 to 1.1. Excess sulfuric acid need not be used to reduce or avoid the production of spent acid solutions.
The amount of the sulfuric acid solution may be 1 to 10 times, preferably 2 to 5 times, more preferably 3 to 4 times the weight of the crude long-chain amino acid. Too much sulfuric acid solution may reduce the recovery of the product. The skilled person can optimize the amount of solution by the solubility of the respective salt.
The temperature at which the crude long chain amino acid is dissolved in the aqueous sulfuric acid solution may be from 50 ℃ to the boiling temperature of the solution, preferably from 60 to 95 ℃, most preferably from 80 to 90 ℃, and activated carbon or filter aids may be added to de-pigment and adsorb impurities. After filtration at the preferred temperature, a clear solution can be obtained.
Alternatively, the sulfuric acid solution of crude long chain amino acids may be extracted with an organic solvent to remove impurities. At the same time, almost all of the pigment material entered the extract phase and the aqueous phase was almost colorless.
Suitable extraction solvents are water-insoluble and may be esters, aliphatic, aromatic, ethers, C4-C10 alcohols and C4-C10 ketones. Useful solvents include, but are not limited to: butyl formate, isobutyl formate, butyl acetate, isobutyl acetate, propyl acetate, isopropyl acetate, ethyl propionate, octyl acetate, benzene, toluene, xylene, cumene, anisole, diethyl ether, isopropyl ether, dibutyl ether, methyl tert-butyl ether, ethyl tert-butyl ether, methyl tetrahydrofuran, petroleum ether, cyclohexane, dichloroethane, dichloromethane, chloroform, carbon tetrachloride, trifluoromethylbenzene, n-butanol, isobutanol, pentanol, isoamyl alcohol, hexanol, cyclohexanol, 2-ethylhexanol, isooctanol, sec-octanol, butanone, pentanone, hexanone, cyclohexanone, methyl isobutyl ketone. One or a mixture of two or more of the above solvents may be used as the extraction solvent.
Preferably, the extraction solvent is toluene.
The clarified solution after treatment with activated carbon or filter aid or extraction is neutralized to a pH of 5-9, preferably 6-8, with an alkaline agent. The temperature of the neutralization operation may be from room temperature to the boiling temperature of the solution, preferably from 50 to 90 ℃ and more preferably from 70 to 80 ℃. The crystal particles of the product obtained at the preferred temperature are larger, more favorable for filtration and separation, and more important, the product purity is higher.
In a further embodiment of the invention, the clear solution obtained after treatment with activated carbon or filter aid or extraction is cooled to precipitate crystals of the salt of the long chain amino acid, and the cooling crystallization of this solution is known in the art. The crystallization suspension is further lowered to room temperature or lower to complete crystallization. The crystals of the salt of the long-chain amino acid obtained are subjected to solid-liquid separation (such as filtration or centrifugation) to obtain a product, and the product is washed with water.
To recover the long chain amino acid, a salt of the long chain amino acid is dissolved or dispersed in water, and then neutralized with an alkaline reagent to adjust the pH to 5 to 9, preferably 6 to 8. The temperature of the neutralization process may range from room temperature to the boiling temperature of the solution, preferably from 50 to 90 c, more preferably from 70 to 80 c. The crystal particles of the product obtained at the optimized temperature are larger, the filtration separation is more facilitated, and the product purity is higher.
The alkaline reagent comprises alkali hydroxide, ammonia water, and bicarbonate, carbonate, bisulfite, sulfite or mixture of two or more thereof. Preferably, the alkaline agent is ammonia or aqueous ammonia.
After the neutralization is completed, the crystal suspension is cooled to room temperature to fully precipitate the product. The neutral long-chain amino acid is recovered in a solid-liquid separation mode, and the product is washed by deionized water.
Drawings
FIG. 1 is a graph of the solubility of 11-aminoundecanoic acid in water and two different concentrations of aqueous acetic acid (5%;
FIG. 2 is a graph of the solubility of 12-aminododecanoic acid in water and two different concentrations of aqueous acetic acid (5% wt/wt and 10% wt/wt);
FIG. 3 is a graph showing the solubility curves of 11-aminoundecanoic acid and 12-aminododecanoic acid in 1M sulfuric acid as bisulfate salts.
Detailed Description
The following examples are specific procedures for the present invention, but the present invention is not limited to the scope of the operation of the specific examples.
Example 1
40g of 11-aminoundecanoic acid was added to 100mL of a 10% (wt/wt) aqueous acetic acid solution, the suspension was warmed to 90 ℃ to give a slightly turbid solution, and then 1g of activated carbon was added. The solution was stirred at 90 ℃ for 1 hour and then filtered hot to give a clear, colorless solution. And slowly cooling the solution to room temperature, separating out a large amount of crystals, filtering, and washing the product with deionized water for 3 times. Drying to obtain 36g 11-aminoundecanoic acid product with purity of 99.6%.
Example 2
30g of 12-aminododecanoic acid was added to 100mL of a 10% (wt/wt) aqueous solution of acetic acid, the suspension was warmed to 90 ℃ to give a slightly turbid solution, and then 0.75g of activated charcoal was added. The solution was stirred at 90 ℃ for 1 hour and then filtered hot to give a clear colorless solution. And slowly cooling the solution to room temperature, separating out a large amount of crystals, filtering, and washing the product with deionized water for 3 times. Drying to obtain 28g of 12-aminododecanoic acid product with the purity of 99.7%.
Example 3
40g of the mixture (11-aminoundecanoic acid: 10-aminodecanoic acid =80%:20% (wt/wt)) were added to 100mL of a 10% (wt/wt) aqueous acetic acid solution, the suspension was warmed to 90 ℃ to give a slightly turbid solution, and then 1g of activated carbon was added. The solution was stirred at 90 ℃ for 1 hour and then filtered hot to give a clear, colorless solution. And slowly cooling the solution to room temperature, separating out a large amount of crystals, filtering, and washing the product with deionized water for 3 times. Drying yielded 35g of product mixture (11-aminoundecanoic acid: 10-aminodecanoic acid =83%:17% (wt/wt)).
Example 4
40g of the crude 11-aminoundecanoic acid are added to 100mL of 1M aqueous sulfuric acid and the suspension is warmed to 90 ℃ to give a slightly turbid solution. 50mL of toluene was added to the above solution and stirred vigorously for 1 hour. Standing for phase separation, and filtering the hot water phase to obtain a clear and colorless solution. Cooling to separate out great amount of bisulfate crystal and cooling the suspension to room temperature.
The crystals were filtered, washed with deionized water, then added to 100mL of deionized water, the resulting suspension was warmed to 80 ℃ and 25% ammonia was slowly added dropwise to adjust the pH of the suspension to 6.8. The solution was then cooled to room temperature to obtain a large amount of 11-aminoundecanoic acid crystals. Filtered and washed 3 times with deionized water. Drying to obtain 35g of white 11-aminoundecanoic acid product with a purity of 99.7%.
All of the embodiments, explanations and illustrations described above are for the purpose of example only. Various modifications based on the technology of the present invention will be apparent to those skilled in the art of chemistry, and such modifications are intended to be included within the scope of the right and claims of this application.
Claims (9)
1. A process for purifying a long chain amino acid having the structure:
wherein m is an integer from 6 to 20; r 1 And R 2 Are H or C, respectively 1 -C 12 In an aqueous solution of a mineral acid, the process comprising the following features:
(1) Dissolving long-chain amino acid by heating inorganic acid aqueous solution;
(2) Adding activated carbon or a filter aid or an extraction solvent into the solution in the step (1) for treatment;
(3) Cooling the solution of step (2) to crystallize a salt of the long chain amino acid;
(4) Separating the salt of the long-chain amino acid obtained in the step (3) by a solid-liquid separation method;
(5) Neutralizing the salt of the long-chain amino acid of the step (4) with an alkaline reagent to obtain the long-chain amino acid.
2. The process of claim 1 wherein the mineral acid is sulfuric, hydrochloric, hydrobromic, nitric or phosphoric acid, and mixtures of two or more thereof.
3. The process of claim 1, wherein the mineral acid is sulfuric acid.
4. The process as claimed in claim 1, wherein the molar ratio of the inorganic acid to the long-chain amino acid is 0.1 to 10.
5. The process as claimed in claim 1, wherein the molar ratio of the inorganic acid to the long-chain amino acid is 0.9 to 1.1.
6. The process of claim 1, wherein the extractive solvent is butyl formate, isobutyl formate, butyl acetate, isobutyl acetate, propyl acetate, isopropyl acetate, ethyl propionate, octyl acetate, benzene, toluene, xylene, cumene, anisole, diethyl ether, isopropyl ether, dibutyl ether, methyl tert-butyl ether, ethyl tert-butyl ether, methyl tetrahydrofuran, petroleum ether, cyclohexane, dichloroethane, dichloromethane, chloroform, carbon tetrachloride, trifluoromethylbenzene, n-butanol, isobutanol, pentanol, isoamyl alcohol, hexanol, cyclohexanol, 2-ethylhexanol, isooctanol, sec-octanol, butanone, pentanone, hexanone, cyclohexanone, or methyl isobutyl ketone, or a mixture of two or more of the foregoing extractive solvents.
7. The process of claim 1 wherein the extraction solvent is toluene.
8. The process of claim 1, wherein the alkaline agent is an alkaline hydroxide, aqueous ammonia, ammonium bicarbonate, carbonate, bisulfite or sulfite, or a mixture of two or more of the foregoing alkaline agents.
9. The process of claim 1, wherein the alkaline agent is ammonia or aqueous ammonia.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US15/686,500 US10239823B2 (en) | 2017-08-25 | 2017-08-25 | Process for purifying long chain amino acids |
| US15/686,500 | 2017-08-25 | ||
| PCT/US2018/039141 WO2019040177A1 (en) | 2017-08-25 | 2018-06-22 | Process for purifying long chain amino acids |
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| Publication Number | Publication Date |
|---|---|
| CN111032623A CN111032623A (en) | 2020-04-17 |
| CN111032623B true CN111032623B (en) | 2023-02-03 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201880054827.7A Active CN111032623B (en) | 2017-08-25 | 2018-06-22 | Process for purifying long-chain amino acid |
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| Country | Link |
|---|---|
| US (1) | US10239823B2 (en) |
| EP (1) | EP3672935A4 (en) |
| CN (1) | CN111032623B (en) |
| WO (1) | WO2019040177A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10239822B2 (en) | 2017-06-28 | 2019-03-26 | Vitaworks Ip, Llc | Process for the separation of long chain amino acids and dibasic acids |
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| US10329242B2 (en) * | 2017-08-25 | 2019-06-25 | Vitaworks Ip, Llc | Process for purifying long chain amino acids |
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2017
- 2017-08-25 US US15/686,500 patent/US10239823B2/en active Active
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- 2018-06-22 EP EP18848738.3A patent/EP3672935A4/en not_active Withdrawn
- 2018-06-22 CN CN201880054827.7A patent/CN111032623B/en active Active
- 2018-06-22 WO PCT/US2018/039141 patent/WO2019040177A1/en unknown
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| CN105541953A (en) * | 2016-03-15 | 2016-05-04 | 成都市新功生物科技有限公司 | Recrystallization purification method for high-purity obeticholic acid |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111032623A (en) | 2020-04-17 |
| EP3672935A4 (en) | 2021-08-18 |
| EP3672935A1 (en) | 2020-07-01 |
| US20190062265A1 (en) | 2019-02-28 |
| US10239823B2 (en) | 2019-03-26 |
| WO2019040177A1 (en) | 2019-02-28 |
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